Mail is generally automatically sorted by an operation termed "delivery point sequence". Mail is generally placed in a postal tray which is transported along the delivery route in a postal delivery vehicle. As the postal delivery person reaches a delivery location, the mail addressed to that location is removed from the tray and delivered. As the mail is removed from the conventional postal tray, the remaining mail items can become disorganized as the removed mail will cause the remaining mail to no longer remain upright in an organized manner but will fall to a flat position on the bottom of the tray.
The conventional postal tray is generally rectangular having an open top with openings at either end which serve as handles. The material of the tray is generally a light weight corrugated material and several official tray designs are in use which are designated the "EMM" and "MM". While these postal trays work well, are light weight and convenient to use in a delivery vehicle, the conventional trays have the disadvantage that the flat mail, letters, and the like are not maintained in a convenient upright position but rather may often assume a flat position making it necessary for the delivery personnel to manually search through the remaining mail for the items to be delivered to the next succeeding mail patron. This can occur if the trays are only partially filled during the initial sorting operation and also occurs as filled trays are emptied during the delivery operation.
A number of approaches to solving the problem dealing with conveniently maintaining mail in an easily accessible position can be found in the prior art. In some cases, individual postal delivery personnel may carry some type of cardboard or wood separator which are used to assist in maintaining the mail in a generally vertical position.
There are various approaches to organizing mail for delivery which can also be found within the patent literature. U.S. Pat. No. 4,643,306 teaches a postal tray provided with individual tray dividers for sorting and delivery of the mail.
Similarly, U.S. Pat. No. 3,491,909 teaches a method and apparatus of separating a tray or enclosure into individual compartments.
Benoit in U.S. Pat. No. 3,746,181 shows a series of individual separators each separator having a base portion. The base portion of the separator is loaded with articles to maintain it in place. This type of separator is designed for static storage of articles.
U.S. Pat. No. 4,889,397 shows a mail delivery system including a plurality of portable trays each having a bottom, an open top and at least two rigid and oppositely disposed sides affixed to the bottom, at least one open side and a gate member to open and close the open side. Separators are removably attached to at least the bottom. Regularly spaced slots within the bottom receive the separators. At least one set of handle members assist in the transportation of the portable tray and assist in the withdrawal or insertion of the portable tray from holder members arranged to receive the tray. A tray case containing a plurality of holder members to removably receive the plurality of portable trays, members for raising and lowering the case and the trays from the loading position to a sorting position are provided. A transport member containing a plurality of holder members to receive the portable trays and transport the portable trays from the tray cases to a tray rack are provided in a delivery vehicle.
A mail sorting rack is shown in U.S. Pat. No. 4,484,685 which has a rack structure with a plurality of parallel divider blades between which the postal worker inserts mail pieces for various addresses in order. A tray underlies the mail which enables the mail worker to pull the tray free of the extending blades eliminating the dividers from the sorted mail so the worker may more easily group and band them for delivery.
U.S. Pat. No. 5,207,347 shows a postal tray adjustable organizer having a translucent framework having an upright and flat bottom portion slidably affixed within the cavity of the postal tray. A finger-operated spring loaded shaft extends outwardly against the sides of the postal tray. The user may grasp the release handles of the spring loaded shaft and the organizer may be slid forward along the tray to secure the mail in an upright position.
Therefore, while the prior art suggests various approaches to the problem of maintaining mail in an organized, easily-identifiable arrangement, these prior art arrangements have not generally been embraced by the Post Office department for a number of reasons. Many of these devices are cumbersome, impair the visual identification of the mail. Further shortcomings of prior art devices is that they do not adapt themselves for use with the conventional light weight, flexible postal trays which are in use today such as the EMM and MM trays.